Each individual has a heart that beats during any given moment at a certain rate generally measured in beats per minute. The heart rate of each individual, however, is generally not constant. Instead, an individual's heart rate varies typically from beat to beat. Tile variation in heart rate is referred to as Heart Rate Variability (HRV). HRV depends upon moment to moment influences of sympathetic and parasympathetic activity of an individual's body. HRV is integral to an individual's response to a wide range of daily influences, including those due to external environment, and those factors directly associated with an individual including breathing patterns, internal physiology, and psychology. An individual's ability to adapt to these influences is directly related to HRV. Thus, HRV can be an important indicator of an individual's fitness level or health condition.
For instance, impairment of an individual's adaptive abilities may lead to development of cardiac, respiratory and immune disorders. Many disorders typically result in decreased HRV of the individual. Decreased HRV relates to many disorders including hypertension, ventricular arrhythmia, heart disease, including myocardial infarction and congestive heart failure, diabetes, sudden infant death syndrome, chronic fatigue, panic disorder, and impending death caused by these and other disorders. The decrease in HRV in these and other disorders typically is related to a decrease in parasympathetic activity, an increase in sympathetic activity, or a disruption in how these two systems interact with one another.
Many health and fitness conditions could be improved if HRV of an individual was known by the individual throughout the day. Feedback given to an individual based on proper monitoring of HRV could then prompt some type of immediate corrective or therapeutic action by the individual. For instance, corrective or therapeutic action could be applied in areas including heart conditions, diabetes, sudden infant death syndrome, chronic fatigue, panic disorder, and respiration.
Unfortunately, prior art devices which monitor HRV are not conducive for use during normal activities throughout the day and night by individuals. Typically, individuals being monitored by prior art devices must go to a clinic or hospital where an HRV monitor is located. Also, these prior art devices do not provide feedback to individuals being monitored. Other prior art devices have been portable, however, these devices determine only heart rate levels but not HRV. Neither the measurement capabilities nor the feedback criteria involve HRV since only absolute levels of heart rate are of interest with these prior art portable devices. The limited accessibility with the lack of feedback of prior art monitors and the lack of HRV monitoring of other prior art devices does not alert individuals of HRV conditions during their normal activities throughout the day and night. Thus, opportunities to improve health and fitness conditions of individuals remain unfulfilled.